https://docs.oracle.com/en/java/javase/13/ specifications--->language and VM
javase14-javase6 version: https://docs.oracle.com/javase/specs/index.html
The Java Virtual Machine Specification, Java SE 13 Edition
docker: https://hub.docker.com/
reactive：https://spring.io/reactive
vps：linode.com digitalocean.com vultr.com 忍者云 佛跳墙 aws azure